Auto-pull DMR models in non-interactive mode and improve user_prompt dialog

DMR model pull (fixes #1856):
- Auto-pull missing models in non-interactive mode (devcontainers, CI)
  instead of silently skipping the pull
- Extract confirmModelPull to separate confirmation logic from pull logic
- In interactive mode, prompt the user as before

user_prompt TUI dialog:
- Rename dialog title from 'MCP Server Request' to 'Question' by default,
  and add a 'title' argument to customize it
- Add a free-form text input field when no schema is provided
- Change navigation keys: tab/shift-tab between fields, up/down within fields
- Update help text and tests accordingly

Assisted-By: cagent

Author: dgageot

pkg/model/provider/dmr/client.go

@@ -971,35 +971,18 @@ func parseDMRProviderOpts(cfg *latest.ModelConfig) (contextSize *int64, runtimeF
 }
 
 func pullDockerModelIfNeeded(ctx context.Context, model string) error {
-	// Check if running in interactive mode (stdin is a terminal)
-	interactive := term.IsTerminal(int(os.Stdin.Fd()))
-	if !interactive {
-		// In non-interactive mode (CI / Servers), do not attempt to pull the model
-		return nil
-	}
-
 	if modelExists(ctx, model) {
 		slog.Debug("Model already exists, skipping pull", "model", model)
 		return nil
 	}
 
-	// Prompt user for confirmation in interactive mode
-	fmt.Printf("\nModel %s not found locally.\n", model)
-	fmt.Printf("Do you want to pull it now? ([y]es/[n]o): ")
-
-	response, err := input.ReadLine(ctx, os.Stdin)
-	if err != nil {
-		return fmt.Errorf("failed to read user input: %w", err)
+	if err := confirmModelPull(ctx, model); err != nil {
+		return err
 	}
 
-	response = strings.TrimSpace(strings.ToLower(response))
-	if response != "y" && response != "yes" {
-		return fmt.Errorf("model pull declined by user")
-	}
-
-	// Pull the model
 	slog.Info("Pulling DMR model", "model", model)
 	fmt.Printf("Pulling model %s...\n", model)
+
 	cmd := exec.CommandContext(ctx, "docker", "model", "pull", model)
 	cmd.Stdout = os.Stdout
 	cmd.Stderr = os.Stderr
@@ -1013,6 +996,30 @@ func pullDockerModelIfNeeded(ctx context.Context, model string) error {
 	return nil
 }
 
+// confirmModelPull asks for user confirmation in interactive mode.
+// In non-interactive mode (e.g. devcontainers, CI), it proceeds automatically.
+func confirmModelPull(ctx context.Context, model string) error {
+	if !term.IsTerminal(int(os.Stdin.Fd())) {
+		slog.Info("Model not found locally, pulling automatically (non-interactive mode)", "model", model)
+		return nil
+	}
+
+	fmt.Printf("\nModel %s not found locally.\n", model)
+	fmt.Printf("Do you want to pull it now? ([y]es/[n]o): ")
+
+	response, err := input.ReadLine(ctx, os.Stdin)
+	if err != nil {
+		return fmt.Errorf("failed to read user input: %w", err)
+	}
+
+	response = strings.TrimSpace(strings.ToLower(response))
+	if response != "y" && response != "yes" {
+		return fmt.Errorf("model pull declined by user")
+	}
+
+	return nil
+}
+
 func modelExists(ctx context.Context, model string) bool {
 	cmd := exec.CommandContext(ctx, "docker", "model", "inspect", model)
 	var stderr bytes.Buffer